Well, there was this one time in a playthrough I modded. I used a humanoid creature the size of an ant. He started as a peasant outsider with maximum agility, and was in a world where hostile creatures such as megabeasts were cranked up nearly to the max. Now, his starting location was in some freezing, dried-out dwarven hamlet in the middle of mountains, and the nearest known place that was warm enough to get a safe drink was all the way to the far west, thus forcing venture much earlier than normal. So I just grabbed a bag with some food from town (somehow, despite his size) and left.
Being tiny and with no combat training, even a small bird could strangle him with ease at this point; his only natural defenses were lack of blood (necessary, really, since even the tiniest of flesh wounds would kill him otherwise) and a few bonus points in ambush and dodge. So for extra safety, I decided to just sneak across, making sure to take a path that at least allows stops if they were necessary. This path also lead me almost directly to a fortress, where the only useable things I found were a quiver (which he could wear, oddly enough) and, to great joy, some steel bolts.
So off he went, traversing through frozen wilderness, only getting in some trouble by alerting a family of wild pigs yet Mr . Small escaped from that easily. Eventually, I got weary of all this walking, and it was getting tedious to do stuff like safely look at different z-levels to check for danger. I decided to just hold down the movement key and casually look for any potential threats on screen while heading to the next stop. I got careless.
Next thing I know, the combat log flared with activity. The screen blinked for a tick once I reacted, and before I knew it poor Mr. Small lost his whole right arm. I looked to see just what was creating all this ruckus and, to my horror, found out that it was a Naga, a monster I also modded in.
Things were looking grim. Here was Mr. Small knocked down on the floor in pain while a monster the size of a Tiger Shark and with six arms just finished spitting out his limb. I panicked and had him stand up immediately. In response, the Naga gave him a deadly high five, sending flying and just barely inches from falling off the hill. Fortunately, this caused minimal damage, but bynow he gave into his pain. She could have easily squished him or at least strangled him at this point, but for some reason the Naga decided to grab onto the tiny guy with all her limbs while he was waking, maybe in some cruel game (but obviously just a quirk of the AI). Desperate times called for desperate measures. I did what any other DF player would do in such a desperate situation: throw shit at things.
Mind you, this was still a long shot. Mr. Small just started his adventuring career, and had no combat skills aside from dodge, while Nagas are naturally ferocious warriors, about on par with Minotaurs. Still, any chance is better than none, so I atempted the Hail Mary Pass with a steel bolt, and managed to connect... on one of her many hands. This seemed like a cruel tease from fate, and I was just ready to quit, but luckily the hit caused the Naga just enough pain to knock her out in an instant.
This looked like just the reversal I needed. I quickly had Mr. Small wield one of the bolts, trying to strike down the beast before he can succumb to his wounds again. I attempted to pierce the head, of course, making numerous attempts to get to those brains, but I should have known better. Mr. Small was simply too little and weak to get through that thick skull of hers, even with steel. He fell down from the pain again, yet by the time he got up the Naga was still unconscious. That seemed like cue enough to leave ASAP, but just after a few steps, she got up again, barreling right to her prey.
Mr. Small stood his ground, throwing some more bolts with his remaining hand, but as feared, she nimbly avoided them this time by the time she closed in. The beast quickly bore down on him, knocking him off his feet and grabbing on to one of his legs. It seems she was done with games, for this time she immediately snapped his leg like a twig. This seemed hopeless again, and with what I thought was going to be Smalls' last act, he threw another bolt. This time, it connected, right into the bone of one of her upper arms, and once again just enough for the Naga to give in to pain.
It looked like this scene was repeating over and over. Once more both laid unconscious, Mr. Smalls recovering first. Either one could sleep or wake at any moment. Even more panicked, I tried the old head trick again, and of course that didn't work. Now in retrospect, I should have gone for the eyes or throat by this time, but again, fear took over. I tried the upper body several times, but only managed to bruise a lung at worst, IIRC. I decided for some reason to go for the arms and hands, since they worked fine before, and as we would have it, they connected enough to put those parts at red. I managed to get her tail too. There was only one arm left when, you guessed it, the little guy fell asleep again.
For some time, both cycled through a series of waking a turn and immediate unconsciousness. By the time I regained control, I attempted for him to make a break for it again. In only two steps, the Naga got up once more, and I was anticipating another last stand. But, I'm not sure if she was filled with fear, or pragmatism , or respect for her quarry, but she also decided to turn tail, crawling the other way in a bloody mess.
As both parted ways, the combat log was filled with messages of both waking and going unconscious. Eventually, Mr. Small managed to escape, crawling to a nearby town just before sunset, and drinking from the blood of his near-nemesis (the only drink he's had since the start, in fact). He survived, managing to recover from most his injuries, and even built himself into a legendary megabeast-killing hero like any other adventurer despite his small size and lack of an arm or wearable armor. I never did find out what happened to that Naga, and although Smalls did kill a number her species I doubt any of them were her. Still, if she survived, I'm sure that, to her embarrassment, this event or at least her injuries created quite the gossip at her local Naga Salon.